Question

What is correlation? Describe its types with suitable example.

Answer 1

If the change in one variable appears to be accompanied by a change in the other variable, the two variables are said to be correlated and this inter­dependence is called correlation or covariation.

To measure the degree of relationship or covariation between two variables is the subject matter of correlation analysis. Thus, correlation means the relationship or “going- togetherness” or correspondence between two variables.1. Positive, Negative or Zero Correlation:

When the increase in one variable (X) is followed by a corresponding increase in the other variable (Y); the correlation is said to be positive correlation. The positive correlations range from 0 to +1; the upper limit i.e. +1 is the perfect positive coefficient of correlation.

The perfect positive correlation specifies that, for every unit increase in one variable, there is proportional increase in the other. For example “Heat” and “Temperature” have a perfect positive correlation.

2. Linear or Curvilinear Correlation:

Linear correlation is the ratio of change between the two variables either in the same direction or opposite direction and the graphical representation of the one variable with respect to other variable is straight line.

Consider another situation. First, with increase of one variable, the second variable increases proportionately upto some point; after that with an increase in the first variable the second variable starts decreasing